1. Field of the Invention
The present invention relates to a system for monitoring predetermined operating conditions of a heating apparatus, such as a cumulative total time period of combustion and a combustion frequency, and informing a user of a timing of maintenance.
2. Description of the Related Art
Conventionally proposed devices as disclosed in JAPANESE PATENT LAYING-OPEN GAZETTE Nos. 2-4128 and 2-33520 monitor a heating apparatus to detect troubles and failures developed therein, and store and display types of such troubles and frequency of occurrence. All such devices monitor the heating apparatus only for taking countermeasures against the troubles which have already been developed, and are not capable of preventing such troubles to improve the durability or operating conditions of the heating apparatus.
There are only a few monitor systems proposed for monitoring a heating apparatus to detect operating conditions thereof. FIG. 6 schematically shows a structure of such a conventional monitor system incorporated in a hot water heater 10. When a user opens a faucet 101, cold water starts running through a cold water supply pipe 102 to turn a water flow switch 103 on. The turn-on operation of the water flow switch 103 opens both a main solenoid valve 104 and a primary solenoid valve 105 for receiving gas through a gas conduit 113 and activates an igniter 106 leading to discharge from an ignition electrode 107 for ignition. A burner controller 108 then compares a temperature detected by a water temperature sensor 109 attached to a hot water supply pipe 110 with a fixed temperature previously set in a remote control 111, and adjusts an opening of a proportional solenoid valve 112 based on the difference between the temperature measured and the fixed temperature. The opening of the proportional solenoid valve 112 here represents an amount of combustion. Through this feed-back control for adjusting the amount of combustion according to the deviation of the temperature, the temperature of hot water running from the faucet 101 is set approximately equal to the fixed temperature. When the user closes the faucet 101, the water flow switch 103 is turned off to close the main solenoid valve 104 and the primary solenoid valve 105 to stop supplying hot water.
The hot water heater 10 is further provided with a conventional heat exchanger 114, a flame rod 115 for detecting flame, a fan (not shown) for supplying the air to a burner, and a bimetal thermostat (not shown) for detecting overheat.
The monitor system of the hot water heater 10 shown in FIG. 6 has a timer 150 and a counter 151, both of which are externally connected to the main solenoid valve 104 for controlling combustion of the hot water heater 10. The timer 150 measures a time period when power is supplied to the main solenoid valve 104 while the counter 151 counts a frequency of power supply to the main solenoid valve 104.
Such a conventional monitor system requires separate measuring devices such as the timer 150 and the counter 151, which increases the manufacturing cost and makes the hot water heater undesirably bulky.